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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #363963

Title: Traits link drought resistance with herbivore defense and plant economics in two semiarid grasslands: The central role of leaf dry matter content

item Blumenthal, Dana
item MUELLER, KEVIN - Cleveland State University
item Kray, Julie
item OCHELTREE, T - Colorado State University
item Augustine, David
item WILCOX, K - University Of Wyoming

Submitted to: Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2020
Publication Date: 6/25/2020
Citation: Blumenthal, D.M., Mueller, K., Kray, J.A., Ocheltree, T.W., Augustine, D.J., Wilcox, K.R. 2020. Traits link drought resistance with herbivore defense and plant economics in two semiarid grasslands: The central role of leaf dry matter content. Journal of Ecology.

Interpretive Summary: We test how plant traits that regulate drought responses are related to herbivore defense and plant growth in semiarid shortgrass steppe and mixedgrass prairie. We find that drought tolerance and escape are opposing strategies in these rangeland ecosystems, each associated with multiple traits. Drought-tolerant plants also tend to be resistant to herbivory, and slow with respect to their potential growth rates. Plants that escape summer droughts via earlier leaf dieback tend to be susceptible to herbivory and have faster potential growth rates. These results fill key conceptual (drought vs. other functions) and geographical (semiarid grasslands) gaps in our understanding of plant traits. They will enable scientists and land managers to predict effects of management and climate on the drought resistance, productivity, and forage quality of these extensive rangelands.

Technical Abstract: To predict the future of semiarid ecosystems, it is essential to understand how drought tolerance, avoidance and escape are related to other key functions such as growth and herbivore defense. The hypothesis that drought and herbivory exert convergent selection pressures has been supported for morphological traits, but is largely untested for structural and physiological traits. We also have limited understanding of how drought traits are related to the plant economic spectrum. Here we address these uncertainties in semiarid shortgrass steppe and mixedgrass prairie. Results reveal coordination between drought tolerance and other functions: drought-tolerant species (low leaf osmotic potential and high leaf dry matter content) were also herbivore-resistant (high leaf toughness and lignin) and ‘slow’ on the economic spectrum (low leaf nitrogen, leaf phosphorus, specific leaf area, and high stem density). Conversely, drought escape through early senescence was associated with lower drought tolerance, lower herbivore resistance, and ‘fast’ economic traits. Leaf dry matter content appears to be a key trait in these semiarid grasslands, differentiating species along multiple axes of function. Strong trait covariation suggests that changes in land management and climate will have predictable effects on drought resistance, productivity and forage quality in the western Great Plains.